Summer just got considerably cooler for the 21-and-over crowd. Boozy floats — modern takes on classic floats and milkshakes made especially for adults — are sweetening menus across the country. Here are a few favorites that doubly satisfy:

Along with its traditional milkshakes, malts and floats, 25 Degrees (with locations in Chicago, as well as Hollywood and Huntington Beach, Calif.) serves a bevy of adult-inspired sodas, including a cream soda that combines ginger beer with vanilla liqueur and Maker’s Mark bourbon. The swanky burger-and-wine bar is also known for its spiked shakes. One to try: the Guinness Shake, a perfect blend of vanilla ice cream, house-made chocolate sauce and the namesake stout. www.25degreesrestaurant.com

Colorado-based burger chain Smashburger serves up After-Hours Shakes, mixing Häagen-Dazs ice cream and liqueurs like Kahlúa, crème de menthe and amaretto at its downtown Denver location in the city’s Tabor Center. Despite their name, these frothy concoctions are available all day long — but only at this location. www.smashburger.com

The ideal accompaniment for a burger and hops-salted fries at Monk’s Kettle in San Francisco? Chef Adam Dulye’s Nitrogenated Beer Float. After choosing a stout (or porter or sour ale, among others) on draft and putting it through a double-chamber nitrogen charger — think whipped-cream canister — Dulye or staff then pour the supersmooth brew over locally made Three Twins ice cream tableside for guests to see. www.monkskettle.com